fix: rebase on main and resolve merge conflicts in stdio subprocess logic

Revert "Merge branch 'main' into fix/windows_stdio_subprocess"

This reverts commit d3e0975, reversing
changes made to 1c6c6fb.

Author: theailanguage

README.md

@@ -585,12 +585,15 @@ For low level server with Streamable HTTP implementations, see:
 - Stateful server: [`examples/servers/simple-streamablehttp/`](examples/servers/simple-streamablehttp/)
 - Stateless server: [`examples/servers/simple-streamablehttp-stateless/`](examples/servers/simple-streamablehttp-stateless/)
 
+
+
 The streamable HTTP transport supports:
 - Stateful and stateless operation modes
 - Resumability with event stores
-- JSON or SSE response formats
+- JSON or SSE response formats  
 - Better scalability for multi-node deployments
 
+
 ### Mounting to an Existing ASGI Server
 
 > **Note**: SSE transport is being superseded by [Streamable HTTP transport](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http).

src/mcp/client/stdio/__init__.py

@@ -108,8 +108,7 @@ async def stdio_client(server: StdioServerParameters, errlog: TextIO = sys.stder
     read_stream_writer, read_stream = anyio.create_memory_object_stream(0)
     write_stream, write_stream_reader = anyio.create_memory_object_stream(0)
 
-    try:
-        command = _get_executable_command(server.command)
+    command = _get_executable_command(server.command)
 
         # Open process with stderr piped for capture
         process = await _create_platform_compatible_process(
@@ -179,18 +178,12 @@ async def stdin_writer():
             yield read_stream, write_stream
         finally:
             # Clean up process to prevent any dangling orphaned processes
-            try:
-                if sys.platform == "win32":
-                    await terminate_windows_process(process)
-                else:
-                    process.terminate()
-            except ProcessLookupError:
-                # Process already exited, which is fine
-                pass
+            if sys.platform == "win32":
+                await terminate_windows_process(process)
+            else:
+                process.terminate()
             await read_stream.aclose()
             await write_stream.aclose()
-            await read_stream_writer.aclose()
-            await write_stream_reader.aclose()
 
 
 def _get_executable_command(command: str) -> str:

tests/client/test_stdio.py

@@ -2,17 +2,11 @@
 
 import pytest
 
-from mcp.client.session import ClientSession
-from mcp.client.stdio import (
-    StdioServerParameters,
-    stdio_client,
-)
-from mcp.shared.exceptions import McpError
+from mcp.client.stdio import StdioServerParameters, stdio_client
 from mcp.shared.message import SessionMessage
-from mcp.types import CONNECTION_CLOSED, JSONRPCMessage, JSONRPCRequest, JSONRPCResponse
+from mcp.types import JSONRPCMessage, JSONRPCRequest, JSONRPCResponse
 
 tee: str = shutil.which("tee")  # type: ignore
-python: str = shutil.which("python")  # type: ignore
 
 
 @pytest.mark.anyio